Book Image

Linux for Networking Professionals

By : Rob VandenBrink
1 (1)
Book Image

Linux for Networking Professionals

1 (1)
By: Rob VandenBrink

Overview of this book

As Linux continues to gain prominence, there has been a rise in network services being deployed on Linux for cost and flexibility reasons. If you are a networking professional or an infrastructure engineer involved with networks, extensive knowledge of Linux networking is a must. This book will guide you in building a strong foundation of Linux networking concepts. The book begins by covering various major distributions, how to pick the right distro, and basic Linux network configurations. You'll then move on to Linux network diagnostics, setting up a Linux firewall, and using Linux as a host for network services. You'll discover a wide range of network services, why they're important, and how to configure them in an enterprise environment. Finally, as you work with the example builds in this Linux book, you'll learn to configure various services to defend against common attacks. As you advance to the final chapters, you’ll be well on your way towards building the underpinnings for an all-Linux datacenter. By the end of this book, you'll be able to not only configure common Linux network services confidently, but also use tried-and-tested methodologies for future Linux installations.
Table of Contents (20 chapters)
1
Section 1: Linux Basics
4
Section 2: Linux as a Network Node and Troubleshooting Platform
8
Section 3: Linux Network Services

Constructing an IPS rule

We've mentioned IPS signatures several times, in particular Snort rules – let's take a look at how they are constructed. Let's look at an example rule, which alerts us of a suspicious DNS request that contains the text .cloud:

alert dns $HOME_NET any -> any (msg:"ET INFO Observed DNS Query to .cloud TLD"; dns.query; content:".cloud"; nocase; endswith; reference:url,www.spamhaus.org/statistics/tlds/; classtype:bad-unknown; sid:2027865; rev:4; metadata:affected_product Any, attack_target Client_Endpoint, created_at 2019_08_13, deployment Perimeter, former_category INFO, signature_severity Major, updated_at 2020_09_17;)

The rule is broken into several sections. Starting from the beginning of the rule, we have our rule header:

The Flow section is not shown – Suricata normally only detects flows for TCP data.

This is followed by the rule's Message section:

...